1. Field of the Invention
The present invention relates to a Carbon NanoTube (CNT) structure and a method of manufacturing CNTs, and more particularly, to a CNT structure having CNTs vertically aligned on a substrate and a method of vertically aligning the CNTs.
2. Description of the Related Art
Since the unique structural and electrical characteristics of CNTs were known, CNTs have been used for a variety of devices such as Field Emission Devices (FEDs), back-lights for Liquid Crystal Displays (LCDs), nanoelectronic devices, actuators and batteries.
FEDs are devices that emit light by emitting electrons from an electron emitting source formed on a cathode and by allowing the electrons to collide with and excite a phosphor layer coated on an anode. Recently, CNTs having excellent electron emitting characteristics have been used as electron emitting sources of FEDs. To manufacture an improved FED, the CNTs used for the electron emitting source should have a low driving voltage and a high emission current. For that purpose, the CNTs need to be vertically aligned on the cathode.
Methods of aligning CNTs can be divided into a direct growth-aligning method and an after-growth-aligning method. The direct growth-aligning method can realize a high density nano structure where CNTs are aligned very well by Chemical Vapor Deposition (CVD), but has a disadvantage in needing high temperature processing, so that the direct-growth aligning method has great limitations in applications to electronic devices that use the CNTs.
The after-growth-aligning method includes a method of stacking CNTs through chemical modification of a substrate surface and a method of aligning CNTs using an electric field or a magnetic field. A method has been studied to characterize the surface of a substrate using a variety of lithography processes and selectively arrange CNTs thereon. However, the after-growth-aligning method has difficulty in vertically aligning the CNTs on the substrate. Recently, there has been research with regard to vertically aligning the CNTs on the substrate using chemical bonding through chemical modification of the substrate and the CNTs. However, it has been known that these methods of aligning the CNTs have lots of problems due to the high aspect ratios of the CNTs.